Science-fiction authors are divided into two major classes: those who write for a living, and those who write as a hobby, or for pin money. E E Smith is the outstanding example of the hobby writer. L Sprague de Camp has an independent income as well as two or three professions, despite the fact that the quantity of his writing equaled that of the hacks (those who write for a living) before the war. Some writers, such as Lester del Rey, turn out a story only when they reach the end of their last paycheck. A good number of fans have hit the pro market, some of them becoming regular contributors.